The steps to repro this issue are:
zig build-obj hello.zig -target x86_64-windows-msvc
zig build-exe hello.obj -target x86_64-windows-msvc --subsystem console
-lkernel32 -lntdll
What was happening is that the main Compilation added a work item to
produce kernel32.lib. Then it added a sub-Compilation to build zig's
libc, which ended up calling a function with extern "kernel32", which
caused the sub-Compilation to also try to produce kernel32.lib. The main
Compilation and sub-Compilation do not coordinate about the set of
import libraries that they will be trying to build, so this caused a
deadlock.
This commit solves the problem by disabling the extern "foo" feature
from working when building compiler_rt or libc. Zig's linker code is now
responsible for putting the appropriate import libs on the linker line,
if any for compiler_rt and libc.
Related: #5825
In C, enums are represented as signed integers, so casting from an enum to an integer
should use the "cast integer to integer" translation code path. Previously it used the
"cast enum to generic non-enum" code path, because enums were not being treated as integers.
Ultimately this can produce zig code that fails to compile if the destination type does not
support the full range of enum values (e.g. translated C code that casts an enum value to an
unsigned integer would fail to compile since enums are signed integers, and unsigned integers
cannot represent the full range of values that signed ones can).
One interesting thing that came up during testing is that the implicit enum-to-int cast that
occurs when an enum is used in a boolean expression was parsed as an (int) by some versions of
the zig compiler, and an (unsigned int) cast by others. Specifically, the following code:
```c
enum Foo {Bar, Baz};
// ...
enum Foo foo = Bar;
if (0 || foo) {
// do something
}
```
When tested on MacOS, Linux, and Windows using a compiler built from the Windows Zig Compiler
Dev Kit, the above code would emit a cast to c_uint:
`if (false or (@bitCast(c_uint, @enumToInt(foo)) != 0)) {}`
However when tested on Windows with a Zig compiler built using MSVC, it produces:
`if (false or (@bitCast(c_int, @enumToInt(foo)) != 0)) {}`
In this particular case I don't think it matters, since a c_int and c_uint will have the same
representation for zero, but I'm not sure if this is ultimately the result of
implementation-defined behavior or something else.
Because of this, I added explicit casts in the `translate_c.zig` tests, to ensure that the
emitted zig source exactly matches across platforms. I also added a behavior test in
`run_translated_c.zig` that uses the old implicit casts from `translate_c.zig` to ensure
that the emitted Zig code behaves the same as the C code regardless of what cast is used.
Use case:
zig build-exe non_existent_file.zig
Previous behavior:
error.FileNotFound, followed by an error return trace
Behavior after this commit:
error: unable to read non_existent_file.zig: FileNotFound
(end of stderr, exit code 1)
This turns AllErrors.Message into a tagged union which now has the
capability to represent both "plain" errors as well as source-based
errors (with file, line, column, byte offset). The "no entry point found"
error has moved to be a plain error message.
Positional shared library arguments were not being detected as causing
dynamic linking, resulting in invalid linker lines. LLD did not have an
error message for this when targeting x86_64-linux but it did emit an
error message when targeting aarch64-linux, which is how I noticed the
problem.
This surfaced an error having to do with fifo.pipe() in the cat example
which I did not diagnose but solved the issue by doing the revamp that
was already overdue for that example.
It appears that the zig-window project was exploiting the previous
behavior for it to function properly, so this prompts the question, is
there some kind of static/dynamic executable hybrid that the compiler
should recognize? Unclear - but we can discuss that in #7240.
ZigTypeIdOptional types have a different way of specifying their payload
value depending on whether the child type is a pointer or not (plus some
other special cases).
Fixes#7251
Make gen_const_ptr_struct_recursive aware of the possible presence of
some trailing padding by always bitcasting the pointer to its expected
type.
Not an elegant solution but makes LLVM happy and is consistent with how
the other callsites are handling this case.
Fixes#5398
Make the code used to calculate the variable slot index into the frame
match what's done during the structure layout calculation.
Prevents a few nasty LLVM errors when such types are passed around.
The mismatch between the argument slot type in the frame structure and
the one used in the store operation made the generated code write
garbage over the nearby fields.
Fixes#7104
